Lithium Solid Polymer Electrolyte Batteries

If you have ever owned a PDA, iPod or any other small electrical device the battery power more often then not incorporated a technology called lithium polymer. For example take a look at these HP Compaq iPAQ Batteries at

As you see many of these batteries like many other batteries found at incorporate a technology that is absolutely amazing as it is functional. This amazing technology is contained in the electrolyte solution that is the conducting medium of the battery and the enabler of the direct current (where volts come from in the battery) to power your electronic device. What is so amazing about it is that the conducting metal gel which is enabling the current to flow to and from the electrodes is only tens of micrometers wide (that is smaller then one of your strands of hair)!

A battery as we know it is a device that stores chemical energy and through an electrochemical/electromotive force converts the stored chemical energy into electric energy via a direct current voltage. A battery cell is the most basic electrochemical unit. When we speak of battery cells we know them as a battery whether there is one cell or three in a series.

A battery cell has three basic parts: the anode, the cathode, and an electrolyte solution. In this article we are going to focus specifically on the electrolyte.

The electrolyte solution is a chemical compound (salt, acid, or base) that when dissolved in a solvent forms a solution that becomes an ionic conductor of electricity. In the battery cell the electrolyte solution is the conducting medium in which the flow of electric current between the electrodes takes place by the migrating electrons.

Since the 1970 it has been known that adding salts to polymers can enable the polymer to conduct lithium ion. The material thus can serve as an electrolyte in lithium batteries. Lithium solid polymer electrolyte batteries, when given full measure to the capacity for miniaturization of a fully solid state battery can have the highest specific energy and specific power of any rechargeable technology.

Some of the benefits that lithium solid polymer electrolytes offers are:

  • ease of manufacturing
  • immunity from leakage
  • suppression of lithium dendrite formation
  • elimination of volatile organic liquids
  • mechanical flexibility.

It is in the mechanical flexibility that makes batteries with a lithium solid polymer electrolyte most incredible. The capability of a lithium solid polymer electrolyte to be flexible allows the rechargeable technology to fit in the smallest of systems. With battery designs smaller then a less than half the size of a credit card, the flexibility aspect of the polymer allows the electrolyte to incorporate a multilayer laminate of thin films of metal, polymer, and ceramic, measuring tens of micrometers in thickness (the human hair is about 50 micrometers wide) which can deliver the highest specific energy and specific power of any rechargeable technology of its miniature size.  To understand the how amazing this technology is imagine thin gel like metal smaller then the width of your hair that not only can bend, stretched, and wrapped but can also deliver enough electrical charge to power your iPod, PDA, or Digital Camera and then you will begin to understand the incredible capability of this technology.

Until next time Dan Hagopian,
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